One by one, thousands of mourners and dignitaries filed past the white-lined coffin of slain Kremlin critic Boris Nemtsov on Tuesday, many offering flowers as they paid their last respects to one of the most prominent figures of Russia's beleaguered opposition.

The London graduate believed to be Islamic State (IS) executioner “Jihadi John” once denounced the 9/11 attacks and the 2005 bombings in the British capital, according to an audio recording released Tuesday.

Tens of thousands of people marched in central Moscow on Sunday to honor the memory of opposition leader Boris Nemtsov, who was gunned down near the Kremlin in the highest-profile assassination of Vladimir Putin's rule.

Thousands of Russians prepared Sunday to march through central Moscow in memory of opposition leader Boris Nemtsov who was gunned down near the Kremlin in the highest-profile assassination of Vladimir Putin's rule.

Supporters of Boris Nemtsov were preparing to march through Moscow Sunday afternoon in an outpouring of anger and grief at the brutal murder of the opposition leader and fervent critic of Vladimir Putin, who has vowed to bring the killers to justice.

Russia's top investigative body said Saturday it is looking into several possible motives for the killing of prominent opposition figure Boris Nemtsov, including an attempt to destabilize the state, Islamic extremism, the Ukraine conflict and his personal life.